This renewal application requests continued NCI exploratory grant funding in order to permit continuation of a planning program for the establishment of a clinical research project involving the treatment of cancer with fast neutrons produced by the 76-inch isochronous cyclotron at the University of California, Davis. Major physical modifications and construction of an addition to the facility are necessary in order to make it usable as a clinical research facility. Radiophysics determinations are needed to define the beam characteristics, and radiobiology investigations of these unique particle beams in order to plan patient treatment rationally. The goal of the program (when operational) is to treat human cancer patients, utilizing existing clinical experience in controlled prospective clinical trials.